Slow Cross vCenter vMotion migration speeds on vSphere 8.x
Article ID: 427695
Updated On:
Products
Issue/Introduction
- When performing Cross vCenter vMotions between data centers, you may observe significantly slow migration speeds, even when high-speed networking is available.
- You are migrating between different datacenters and across different datastores.
- This is particularly noticeable with large Virtual Machines (e.g., several terabytes in size) where migrations may take many hours to complete.
- Network throughput tests (like iperf) show high bandwidth availability, but vMotion remains slow.
- You are already using jumbo frames (MTU 9000) and pings with jumbo frames are already validated using the below command.
vmkping -I vmkX 192.168.X.X -d -s 8972
Note: Replace X in vmkX with vmotion vmk number and IP with the destination vmotion vmk.
Environment
VMware vSphere 8.x
Cause
Large-scale migrations involving different storage or data centers may be limited by the efficiency of the default Network File Copy (NFC) transport protocol. While vSphere 8.x includes auto-tuning for vMotion streams, standard vMotion configurations may not fully utilize high-bandwidth links for the initial data sync of large VMs with no UDT activated.
Starting vSphere 8.x, we introduced a new protocol called Unified Data Transport (UDT). In a nutshell, UDT combines the best of the NFC and vSphere vMotion protocols.
Resolution
To optimize migration performance, you can enable the Provisioning service to leverage Unified Data Transport (UDT).
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Log in to the VMware vSphere Client.
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Navigate to the Host > Configure tab.
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Under Networking, select VMkernel adapters.
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Select the VMkernel adapter used for vMotion and click Edit.
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In the Enabled services section, check the box for Provisioning.
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Click OK.
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Repeat these steps for all source and destination hosts involved in the migration.
Note: You may also choose to create a separate, dedicated VMkernel adapter for the Provisioning service if network traffic separation is required by your architectural standards.
If slow speeds persist despite enabling provisioning on both ends and confirming that network throughput is optimal, please feel free to open a case with Broadcom Support Team for further investigation.
Additional Information
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